Ever since my Dog, a Great Dane, Male, 4 year old, Coda, was neutered he has occasionally had a yellow brown discharge drip from the tip of his penis. There are no other symptoms, and it doesn't cause him any noticeable discomfort, no foul smell, no fever, no lack of appetite, no behavioral changes. Nothing.
It's disconcerting to see it, but there doesn't seem to be any outstanding issues with it.
Vet Comment Dog Penis Dishcharge
The type of dog penis discharge that you describe is almost always normal. Coda is still able to produce prostatic fluid and other secretions from his reproductive tract despite being neutered, and these liquids will sometimes collect at the end of the penis.
If the drainage were to be associated with discomfort or other abnormalities, you should bring him in to the veterinarian immediately. However, you say he is completely normal otherwise, so I am not too worried.
It wouldn’t hurt to mention this to your veterinarian the next time Coda is in for a check-up. He or she can examine Coda’s penis and will probably be able to put your mind at ease.